Polymer Science Group, Department of Chemical Engineering, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia.
Department of Biomedical Engineering, University of Melbourne, Parkville, Melbourne, VIC, 3010, Australia.
Nat Commun. 2020 Apr 2;11(1):1630. doi: 10.1038/s41467-020-15312-x.
The high toughness of natural spider-silk is attributed to their unique β-sheet secondary structures. However, the preparation of mechanically strong β-sheet rich materials remains a significant challenge due to challenges involved in processing the polymers/proteins, and managing the assembly of the hydrophobic residues. Inspired by spider-silk, our approach effectively utilizes the superior mechanical toughness and stability afforded by localised β-sheet domains within an amorphous network. Using a grafting-from polymerisation approach within an amorphous hydrophilic network allows for spatially controlled growth of poly(valine) and poly(valine-r-glycine) as β-sheet forming polypeptides via N-carboxyanhydride ring opening polymerisation. The resulting continuous β-sheet nanocrystal network exhibits improved compressive strength and stiffness over the initial network lacking β-sheets of up to 30 MPa (300 times greater than the initial network) and 6 MPa (100 times greater than the initial network) respectively. The network demonstrates improved resistance to strong acid, base and protein denaturants over 28 days.
天然蛛丝的高韧性归因于其独特的β-折叠二级结构。然而，由于加工聚合物/蛋白质以及管理疏水性残基组装所涉及的挑战，制备具有机械强度的富含β-折叠的材料仍然是一个重大挑战。受蛛丝的启发，我们的方法有效地利用了局部β-折叠结构域在无定形网络中提供的卓越机械韧性和稳定性。在无定形亲水性网络中使用从接枝聚合方法，可以通过 N-羧酸酐开环聚合来控制空间生长聚（缬氨酸）和聚（缬氨酸-r-甘氨酸）作为形成β-折叠的多肽。所得连续β-折叠纳米晶体网络在抗压强度和刚度方面均优于初始无β-折叠网络，分别提高了 30MPa（比初始网络高 300 倍）和 6MPa（比初始网络高 100 倍）。该网络在 28 天内对强酸、强碱和蛋白质变性剂的抵抗力有所提高。
